1. Field of the Invention
This invention relates to a positioning information transmitting device for transmitting the positioning information obtained on positioning the current site, to a near-by device(s), and to a positioning information transmitting/receiving system comprised of the positioning information transmitting device and the near-by device(s).
2. Background of the Invention
Up to now, there has been known such a technique for measuring the current site by the global positioning system (GPS) or based on base station signals for a portable telephone set. Such device employing this technique to calculate the current site for practical application has already been commercialized.
The positioning technique by GPS uses C/A (Coarse/Acquisition) codes contained in L1 electrical waves, sent from three or more of 24 satellites performing orbital movements at an altitude of approximately 20,000 km, with a carrier frequency of 1575.42 MHz, to find the distance between a moving object and the satellites to calculate the position of the moving object.
As disclosed in Japanese Laying-Open Patent Publication 2001-45549 or Japanese Laying-Open Patent Publication H-10-322752, the technique of calculating the current site based on received base station signals for a portable telephone set calculates the distance between the base station and the moving object, based on the phase difference of the electrical waves, and calculates the current site by trigonometrical survey on the basis of the calculated distance.
However, the majority of the currently commercialized devices include a unit for measuring the current site, enclosed therein, while it has not been attempted to transmit the positioning information to other devices.
There is presently used a current site measurement unit of the type in which current site data is transmitted by cable communication, such as USB, PC card or serial communication, to a main body device, such as PC or car navigation system. However, this measurement unit communicates with the main body device in the relationship of one-for-one correspondence, such that the current site information is not exchanged with a main body device not paired with respect to the current site measurement unit. Even if the current site data is transmitted to such main body device not paired with respect to the current site measurement unit, there persist complexities that, since cable communication is used, the current site measurement unit must be connected to the main body device over a cable.